ZertES and eIDAS explained: signing electronically with legal effect
Electronic signatures are clearly regulated in Switzerland and the EU — by ZertES and the eIDAS regulation. Both define the available signature levels and when each one is enough. This guide explains the basics in plain terms and shows how letssign.now puts them into practice.
What is ZertES?
ZertES is the Swiss Federal Act on Electronic Signatures (Bundesgesetz über die elektronische Signatur). Together with its accompanying ordinance, it forms the legal framework for electronic signatures in Switzerland.
The act sets out how electronic signatures are created, verified and treated in law. In particular, it defines the recognised signature levels and the requirements for accredited providers that issue qualified certificates. The result is a clear, traceable standard for when an electronic signature carries evidential weight.
- The Swiss legal basis for electronic signatures
- Defines the signature levels and their recognition
- Governs accredited providers for qualified certificates
What is eIDAS?
eIDAS stands for «electronic IDentification, Authentication and trust Services» — the EU regulation on electronic identification and trust services. It applies directly across all EU member states and creates a single framework for electronic signatures in the internal market.
eIDAS and ZertES are deliberately aligned: both recognise the same three signature levels and comparable requirements. As a result, a signature validly created under one framework is broadly recognised under the other in practice. This is not a guarantee for every individual case — actual recognition depends on the contract and the applicable law — but the levels are fundamentally compatible.
- EU regulation for electronic identification and trust services
- Applies directly in every EU member state
- Aligned with Switzerland's ZertES — the levels are fundamentally compatible
SES, AES and QES — the three levels
Both ZertES and eIDAS distinguish three signature levels that differ in evidential weight and effort.
SES (simple electronic signature) is the lowest level — for example a scanned signature image or a click to accept. AES (advanced electronic signature) is uniquely linked to one person, allows that person to be identified, and makes any later changes to the document detectable. QES (qualified electronic signature) is the highest level: it relies on a qualified certificate from an accredited provider and, in certain cases, is treated as equivalent to a handwritten signature.
In the vast majority of business cases, SES or AES are entirely sufficient. A QES is only required where the law expressly demands written form — for example in specific, clearly named types of contract.
- SES — simple signature, for agreements with no required form
- AES — uniquely linked, with identification and tamper-evidence
- QES — highest level, treated as a handwritten signature in certain cases
- SES or AES cover most B2B contracts
How letssign.now implements ZertES and eIDAS
letssign.now offers SES and AES — the two levels that are sufficient for most B2B contracts. We deliberately do not offer QES, because it requires a qualified certificate from an accredited provider.
Every signature is sealed with a PAdES audit trail and a qualified timestamp (TSA). This makes it traceable who signed and when, and any later changes to the document become detectable. Every signed document can be checked independently at any time at /verify.
letssign.now is Swiss-made and hosted in Switzerland — while remaining globally available. With the Branded tier, your customers sign under your own subdomain.
- SES and AES — no QES (sufficient for most B2B contracts)
- PAdES audit trail with a qualified timestamp (TSA)
- Independently verifiable at /verify
- Swiss-made, hosted in Switzerland and globally available
Sign with legal confidence — Swiss-made
Send documents for SES or AES signature, sealed with a PAdES audit trail and a qualified timestamp. Independently verifiable any time at /verify.
Start for freeFrequently asked questions
Is a signature from letssign.now legally valid?
Yes. letssign.now creates SES and AES signatures in line with the levels defined by ZertES and eIDAS. In most business cases such signatures are fully valid and carry evidential weight. Whether a particular level is required in a given case depends on the specific contract and the applicable law.
Does letssign.now offer QES?
No. letssign.now offers SES and AES, but not QES. A QES requires a qualified certificate from an accredited provider. For the vast majority of B2B contracts, SES or AES are entirely sufficient; QES is only needed where the law expressly requires written form.
Is a Swiss signature recognised in the EU — and vice versa?
ZertES and eIDAS are aligned and share the same signature levels. A signature validly created under one framework is broadly recognised under the other in practice. There is no blanket guarantee for every case — actual recognition depends on the contract and the applicable law.
How can I verify a signature?
Every document signed with letssign.now carries a PAdES audit trail and a qualified timestamp (TSA). You can verify it independently at any time at /verify, which shows who signed, when, and whether the document has remained unchanged since.